Add extra_protoc_args attr to plugin, closes #68

aspect.bzl

@@ -414,6 +414,10 @@ def proto_compile_aspect_impl(target, ctx):
                 out_arg = "{}:{}".format(opts_str, out_arg)
         args.add("--{}_out={}".format(plugin_name, out_arg))
 
+        # Add any extra protoc args that the plugin has
+        if plugin.extra_protoc_args:
+            args.add_all(plugin.extra_protoc_args)
+
         # Add source proto files as descriptor paths
         for proto in protos:
             args.add(descriptor_proto_path(proto, proto_info))

plugin.bzl

@@ -1,6 +1,7 @@
 ProtoPluginInfo = provider(fields = {
     "name": "The proto plugin name",
     "options": "A list of options to pass to the compiler for this plugin",
+    "extra_protoc_args": "A list of extra args to pass directly to protoc, not as plugin options",
     "outputs": "Output filenames generated on a per-proto basis. Example: '{basename}_pb2.py",
     "out": "Output filename generated on a per-plugin basis; to be used in the value for --NAME-out=OUT",
     "output_directory": "Flag that indicates that the plugin should just output a directory. Used for plugins that have no direct mapping from source file name to output name. Cannot be used in conjunction with outputs or out",
@@ -20,6 +21,7 @@ def _proto_plugin_impl(ctx):
         ProtoPluginInfo(
             name = ctx.attr.name,
             options = ctx.attr.options,
+            extra_protoc_args = ctx.attr.extra_protoc_args,
             outputs = ctx.attr.outputs,
             out = ctx.attr.out,
             output_directory = ctx.attr.output_directory,
@@ -41,6 +43,9 @@ proto_plugin = rule(
         "options": attr.string_list(
             doc = "A list of options to pass to the compiler for this plugin",
         ),
+        "extra_protoc_args": attr.string_list(
+            doc = "A list of extra args to pass directly to protoc, not as plugin options",
+        ),
         "outputs": attr.string_list(
             doc = "Output filenames generated on a per-proto basis. Example: '{basename}_pb2.py'",
         ),